The pharmacokinetics and tissue distribution of gomphoside in Wistar rats.

The excretion and tissue distribution of [3H]-gomphoside was studied after i.p. and i.v. administration of the cardiac glycoside (1 micrograms/g) to male Wistar rats. Following an intraperitoneal dosage of [3H]-gomphoside, most of the radioactivity (greater than 80%) had been excreted from the body by the end of 48 hours. Biliary excretion played a major role in elimination of [3H]-gomphoside with 90 +/- 15% of radioactivity being collected in 24 hours. Renal excretion formed a minor route of elimination of the cardiac glycoside; only 6 +/- 2% being excreted over 6 days. The distribution of radioactivity to tissues after an intravenous dose was rapid; most of the dose was located in the liver (32%), and the skeletal muscle (31%) 3 minutes after injection. The pharmacokinetics of [3H]-gomphoside could be described by a two-compartment open model with an average elimination half-life of 3.7 hours, and a large volume of distribution (2.3 +/- 0.3 ml/g body weight) characteristic of the commonly used cardiac glycosides (1).